zamanakos



July 9, 1963 A. s. zAMANKos Y 3,097,358

FUSE BEARING ANTENNA Filed Oct. 28, 1960 ARTHUR S. ZAMANAKOS BY MW affATTORNEY United States Patent() 3,097,358 FUSE BEARING ANTENNA Arthur S.Zamanakos, 2809 S. 8th St.,-Arlington, Va.

Filed Oct. 28, 1960, Ser. No. 65,867

Claims. (Cl. 343-119) (Granted under Title 35, U.S. Code (1952), sec.266) must ordinarily 1be made between :the various desirablecharacteristics of the antenna system. For example, -for initialacquisition purposes it desired that the electromagnetic wave couplingsystem be sufficiently broad in anguiar coverage so as to be able .topick up the source of electromagnetic waves and yet at the same time notbe so broad as to possibly pick up an undesired source. Furthermore,once acquisti'on of the desired source of electromagnetic waves hasoccurred it is normally desired that the coupling dewcc have suitable-beamwidth characteristics so as to permit it 'to operate despitepossible evasive tactics of the source of electromagnetic waves and yetnot be misled by other -sources of electromagnetic waves. A furtherdifficulty involved in such a passive homing device is the tremendousvariation in signal intensity encountered as the hom-ing device movesfrom an initial` starting point, which normally is at considerable rangefrom the source of electromagnetic ywaves, to the more highly intensefields existent in proximity to the source of electromagnetic waves.Homing devices ordinarily must employ one of various forms of signalcomparison or lobring techniques whereby it is possible to determinewhether the passive homing device is traveling in the proper directiontoward the source of electromagnetic waves. Such determination also mustnormally be made in two planes where the passive homing device isopera'ble in a medium such that restriction to one plane of travel doesnot occur.

Because of the wide variation Vin signal .intensity encountered as notedin the foregoing, it frequently occurs that a passive homing devicewhich has adequate sensitivity for initial phases of operation will :beoverloaded long before the passive homing device reaches the source ofelectromagnetic waves. Such overload can be manitested in many ways andcan have many different results n depending lupon the specific designVof fthe apparatus. However, in general, it is expected where 'thesource of electromagnetic waves is a powerful radio frequency devicesuch as an enemy operated distant radar transmitter, that the passivehoming device would employ several crystal detector devices in theinitial stages thereof to perform the customary function ofsuperheterodyne receiver mixing -in various comparison channels. In sucha device overload normally is manifested most significantly Iby aburn-out .of 'the crystal mixer devices due to the application ofexcessive electromagnetic wave energy thereto as a result of proximityto the source of high powered electromagnetic wave energy.

By proper design of the receiver system, it -is possible for continuedoperation to be obtained even 'with the mixers reduced towhat wouldnormally be considered a useless condition where low signal levels areinvolved. This is t-rue because the mixer function can be caused totransfer to a less sensitive mixer or some other subsequent stage whichmay have some inherent nonlineairity therein at high signal levels. Sucha condition couldY ice normally occur in any more or less conventionalreceiver vdue to overdlri-ving of grid circuits, anode circuit cutoffand the like, all of which can produce non-linearity at stagessubsequent to the normal mixer stage so that mixing action can beobtained to produce the superheterodyne frequency conversion.

In the superheterodyne system when the mixer crystals of comparisonchannels are overloaded and burn out, it is essential :that the burn-outof crystals in opposing zones of reception occur simultaneously,otherwise the channels associated with the two opposing zones of-reception will have drastically different characteristics, one having aseriously deteriorated crystal mixer and the other a still operablecrystal mixer. This situation is likely to cause sen'ouslyrerroneousguidance information to be derived by the homing device causing it toveer sharply away from the direction of the sou-ree of electromagneticwaves upon which it is homing. It is thus seen that it would bedesirable to provide asystem arrangement wherein such unequaldisablement of opposing comparison channels is avoided and also where ifpossi-ble mixer crystal burn-out could also =be retarded.

It is accordingly an object of the present invention to provide such asystem in which the unequal burn-out of mixer crystals may be avoided. v

Another object of the present invention is to provide a system whereinthe strength of signals applied to a receiver in a passive homing deviceis automatically reduced as extremely high levels signal lintensity areencou-ntered.`

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection' with the accompanying drawings wherein:

FIG. -1 shows a typical embodiment of the features of the presentinvention.

FIG. Z shows in greater detail the configuration of a typical antennasystem embodying the principles of the present invention.

FIG. 3 shows typical details of a fusible link employed in Ithe presentinvention.

With reference now to FIG. 1 of the drawing, the apparatus shown-therein contains a more or less distant source of electromagnetic waveenergy 10 which may produce any conventional form of emission and whichwould normally be entirely independent of the balance of the apparatusof FIG. 1 which is a schematic representation of a passive homing devicesuch as a guided missile identified in general by the numeral 11. Thisdevice 11 will ncrmally contain some suitable form of propulsionapparatus not within the basic teachings of the present invention as tospecific details of improvement thereof and in addition will containsome form of guidance device which is operated upon by apparatus of thepresent -invention as contained within the block 12 which is labeledguidance and control apparatus. Normally the guidance and controlapparatus wouldv be accomplished by the operation of suitableaerodynamic surfaces or selective operation or direction of rocketmotors and the like, to provide for sending the passive homing device111 in the desired direction which is that of the distant signal source10. For guidance purposes in each plane in which the passive homingdevice 11 can be maneuvered, the device 11 has a pair of matched signalreception channels with suitable arrangements for comparing the signalsreceived -by said channels to determine if any correction is necessaryto keep the passive homing device 11 traveling in the direction of thedistant signal source 10. As typiiied in FIG. 1 these channels containthe receiving channel No. 1 apparatus 13 and receiving channel No. 2apparatus 14 each of which will kordinarily because of the frequenciesinvolved in most typical situations contain as :the rst stage thereof acrystal mixer device, such .an arrangement being well known in the artemployed in radar systems for example. 'Ihe output from -the receiverchannels 13 and 14 is compared in a suitable comparison circuit 15,which is not of any great specific importance in the presentexempliiication of the invention, by means of which the receiver outputis compared for the operation of the guidance and control circuits y12.Each receiving channel 13 and 14 has a suitable antenna 16, 17 forinterception of electromagnetic wave energy from the distant signalsource 10.

In accordance with the basic .teachingsof the present invention theantennas 16 and 17 are constructed in such a manner as to include selfdetuning or desensitizing devices of the nature of fuses which burn outsimultaneously upon the attainment of a preselected antenna current toreduce the antenna dimensions in such a way as to also reduce .the mixercurrent and hence avoid burn-out of mixers incorporated within thereceivers 13 and 14. When the antenna detuning devices are constructedi-t is possible to obtain precise control over Ythe fusingcharacteristics because 'this fuse device has yonly one function toperform, as contrasted to the more or less fortuitous burn-out of amixer device,l which is normally selected only for its capabilities ofproviding desirable mixing characteristics and not also upon a basis ofits burn-out current which could not be determined precisely in anyevent except by the destruction of the unit. The fuse art has progressedto a state wherein it is possible to obtain precisely controlled currentburn-out characteristics for a plurality of units.

In a typical embodiment the specific antenna could be of any suitableform desired such =as a dipole or the like. However, the spiral antennahas certain advantages which render it very desirable in connection withthe apparatus of the present invention. The spiral antenna has broadcharacteristics not only with regard to frequency of operation but alsowith regard to beamwidth. Thus the spiral' antenna provides the desiredbroad angle of reception for initial capture or location operation. As aresult of the broad frequency characteristics it is capable of receivingsignals over -a wide frequency range without serious impedance matchingproblems. It does have certain general limitations "however with regardto the periphery thereof and its relationship to the frequency ofoperationv for maximum efficiency. Howeverin this instance the eiciencyis varied by incorporating into the conductors of the spiral antennasfusible elements 22, 23 arid 24, 25 which are designed to burn out whena desired magnirude of antenna current in the elements is reached.

The spiral antenna elements may be described in greater detail as beingtwo conductor archemedian spirals disposed in a plane in which theconductors spiral outward from a central portion of small diameter to alarge diameter outer portion. Connection rto the two conductors is bymeans of suitable lead wires 26, 27 and 28, 29. Typically fthe spiralantennas may be produced by printed circuit techniques wherein thespiral conductors remain as ribbons of conductive material on a suitableprinted circuit base member which is selected for its insulation andstrength properties. The fusible elements 22, 23 and 24, 25 may beconstructed of some suitable resistance wire, and preferably areencapsulated to minimize the deterioration effects of time, heat,humidity and the like. Typically =the fusible elements are selected insuch a manner as to have precisely matched bum-out characteristics andare connected across purposely placed discontinuities in the conductorsof the spiral elements.

When the spiral antenna elements are used prior to burn-out of thefusible members 22, 23, 24 4and 25, the elements have continuousconductors so that the normal gain characteristics of the spiral antennaare experienced. As the passive homing device 11 approaches the signalsource however, eventually a point is reached lat which the signalbecomes so intense that the current in the antenna conductors 16 and 17exceeds the capabilities of the fusible members, at which point burn-outoccurs and the outer portions of the spiral antenna element conductorsare no longer connected to the lead in conductors 26, 27, 28 yand 29.This reduces .-the effective periphery of the spiral antenna element ltoa small portion of the previously existing condition which by selectionas to size on a trial and error basis or by calculation reduces thelsensitivity of the spiral antenna element without producing asubstantial undesired variation in the impedance charatceristics of theuse exemplified herein. Thus the signal applied through the leads 26,27, 28

and 29 to the receiving channels 13 and 14 is reduced in amplitude sothat burn-out of the crystal mixers will not occur. Thus the passivehoming device 11 is permitted to travel to the distant signal source 10without the danger of nonsimultaneous burn-out of crystal mixers in the4receiving, channels 1 and 2.

From the foregoing it is apparent that considerable variation in thespecific structure shown is possible without exceeding the principles ofthe present invention. For example, the -invention as described is notlimited to the typical spiral antenna nor is it limited to devicesemploying single spiral antennas for the receiving channels No. 1 andNo. 2. Specifically the spiral antenna elements employed singly -foreach channel as in FIGS. l and 2 are circular polarization sensitivedevices which in some instances may not be altogether desirableparticularly if the distant signal source 10 is of such a nature as -toproduce linearly polarized signals, in which instance yan antenna systemfor the passive homing device 11 would be desired having linearpolarization characteristics. Where lsuch is encountered it -is alsowithin the teachings of the present invention -to employ a plurality ofantenna elements for each channel, fthe antenna elements being in theform of spiral doublets having linear polarization characteristics. Insuch an instance fusible mem-bers 22, 23, 24, 25 would be employed ineach conductor of each spiral antenna element.

As a fur-ther exemplification of the variations possible with theapparatus of the present invention, in some instances it may bedesirable to apply a deliberate signal lfrom within the passive homingdevice 11 to cause the A burn-out of the various fusible members 22, 23,24 and 30, 31, 32 and 33 whereby a disabling signal may be applied to'all fusible members simultaneously from a disabling circuit 34responsive to the signal level in the yreceiving channel 13 or 14. Thuswhen the signal level in the receiving channel 13 or 14 for examplereaches a selected level Ias sensed by any suitable form of measuringdevice, a signal is delivered to the disabling circuit 34, which may bea suitable threshold circuit and amplier, which is then applied throughthe radio frequency isolating devices 30, 31, 32 and 33 to cause thesimultaneous destruction of all of the fusible members 22, 23, 24 and25.

FIG. 3 exemplifies .the manner in which the fusible elements 22, 23, 24and 25 may be constructed so as to be responsive to such va simultaneousdestruct signal. As shown the fusible member contains la central wire 50which is the heat fusible element having terminals 51 and 52 whichconnect the particular spiral conductor asso-` ciated therewith. 'I'hefusible member 50 is contained within a suitable encapsulation 53 whichmay have suitp passage of antenna current therethrough, will cause aburn-out of the .fusible member 50. Typically one of the leads 55 would`go to the control lead of the disabling circuit 34 whereas the otherlead 56 could go to the ground return of the disabling circuit 34.

`Obviously many modications and variations of the present invention arepossible in thevlight -of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically descri-bed.

What is claimed is:

1. A signal energy coupling system comprising, a plurality of antennacomponents cooperative for high sensitivity with at least one componentoperative individually at lesser sensitivity, a radio Afrequencyoperative device, means connecting one of said antenna components to theradio frequency device, and current responsive means connecting saidantenna components whereby connection between said antenna components isbroken yupon the occurrence of preselected current therethrough.

2. A signal energy coupling system comprising, a spiral antenna having adiscontinuity in at least one conductor thereof, a radio frequency-operative device, means connecting said spiral antenna to `said device,and current responsive means for bridging the -discontinuity in thespiral antenna whereby the connection across the continuity is brokenupon the `occurrence of preselected current flow therethrough. f

3. In apparatus for homing on a source of electromagnetic wave energy,means for comparing two incoming signals :to determine errors of homing,a plurality of antenna components cooperative in pairs for highsensitivity with at least one component of each pair operativeindividually at reduced sensitivity for deriving the two incomingsignals, means connecting .a irst lone of each pair of the antennacomponents to said first named means,

and fusible current responsive disconnect means connecting the second ofeach pair of antenna components respectively to the iirst one of eachpair of antenna components whereby greater overall signal coupling tothe means for comparing is obtained until preselected current isrealized due to proximity of the apparatus to the source, causingdestruction of the fusible current responsive means.

4. In apparatus for homing on a sou-ree of electromagnetic wave energy,a plurality of spiral antennas having a discontinuity in at least oneconductor thereof, means for amplifying signals picked up by theantennas, means for comparing amplied signals from two of the antennasto derive guidance control signals for the homing apparatus, and currentresponsive disconnect means for bridging the spiral antennadiscontinuity whereby the connection across the discontinuity is brokenupon the occurrence of preselected current flow therethrough.

5. In apparatus for homing on a source of electromag-l netic waveenergy, a plurality of spiral 'antennas having, a discontinuity in atleast one conductor of each, means for amplifying signals picked up -bythe antennas, means for comparing amplified signals from two of theantennas -to derive guidance control signals for the homing apparatus, aplurality of current responsive disconnect means for -bridging thespiral antenna discontinuities whereby .the connections across thediscontinuities are broken vupon the occurrence of preselected currentilow there- References Cited in the le of this patent UNITED STATESPATENTS McNatt May 12, 1959 Mueller Nov. 28, 1961

5. IN APPARATUS FOR HOMING ON A SOURCE OF ELECTROMAGNETIC WAVE ENERGY, APLURALITY OF SPIRAL ANTENNAS HAVING A DISCONTINUITY IN AT LEAST ONECONDUCTOR OF EACH, MEANS FOR AMPLIFYING SIGNALS PICKED UP BY THEANTENNAS, MEANS FOR COMPARING AMPLIFIED SIGNALS FROM TWO OF THE ANTENNASTO DERIVE GUIDANCE CONTROL SIGNALS FOR THE HOMING APPARATUS, A PLURALITYOF CURRENT RESPONSIVE DISCONNECT MEANS FOR BRIDGING THE SPIRAL ANTENNADISCONTINUITIES WHEREBY THE CONNECTIONS ACROSS THE DISCONTINUITIESWHEREBY UPON THE OCCURENCE OF PRESELECTED CURRENT FLOW THERETHROUGH, ANDMEANS FOR APPLYING A DESTRUCT SIGNAL TO SAID DISCONNECT MEANS TO CAUSETHE CONNECTIONS THROUGH ALL OF SAID DISCONNECT MEANS TO BE BROKENSIMULTANEOUSLY.